Report Biopolymers and
Report Biopolymers and bioplastics from milk proteins Raw material for the necessary casein is cow’s milk, which has a casein content of 2 to 3 % per weight. One litre of cow’s milk contains about 40 g of butterfat, 36 g of casein and 50 g of lactose. So up to 30 litres of milk are necessary for producing 1 kg of casein, which is a quite inefficient ratio. Pic. 7: Toiletry articles (Metal, glass and Celluloid as replacement for ivory) A kind of an artificial horn, marketed with the brand names Galalith or Erinoid, was made from dried casein in a quite lengthy and costly manner. The production of hard artificial horn required milk properly degreased by centrifuging and precipitated with rennet instead of acid. For hardening, the plates and rods needed to be brought into a 5 % aqueous bath of formaldehyde. The hardening took weeks and months, which made the process so expensive. Later, the hardening was cut by two thirds and later down to 20 % by means of potassium thiocyanate. Pic. 8: Billiard balls (Celluloid as replacement for ivory) Biopolymers und bioplastics from cellulose (cell walls from plants) In the 19 th century, cellulose became an important raw material for plastics. Since the bronze age, cellulose from papyrus, wood and cotton was used as paper, as well as in the form of fibres and textiles. Cellulose can be found as a structural component in all plants – including many plants that are not useful as food. Hence cellulose is the most frequently encountered carbohydrate on earth. Vegetable fibres such as cotton, jute, flax and hemp are cellulose in a nearly pure form. By means of drawing into fibres and forming, it is possible to convert cellulose into paper (pulp). The cellulose used here is obtained from wood or straw. By hydrolysis of cellulose, glucose is obtained, which can then be converted into different chemicals such as acetone, alkanols, carboxylic acids, and also ethanol, by means of fermentation. This bioethanol can deliver ethylene and butadiene for the production of bioplastics. However, the method involves many different steps and is not always efficient. Pic. 9: Picture Frame (Bois Durci as replacement for e.g. Ebony) All pictures by courtesy of Deutsches Kunststoffmuseum, Düsseldorf, Germany. By Christian Bonten Deutsches Kunststoffmuseum Düsseldorf, Germany A simpler method is to produce derivatives from cellulose which can be converted more directly into bioplastics. The esterification to a cellulose ester with the aid of derivatives of organic acids (e. g. acid anhydride) represents a typical method. The characteristics of these cellulose esters can be strongly influenced by additives, e.g. plasticizers. The common cellulose esters CA (cellulose actetate), CAB (cellulose acetate butyrate) and CP (cellulose propionate) can be converted using all known plastics converting processes. 38 bioplastics MAGAZINE [04/14] Vol. 9
Basics Bioplastics (as defined by European Bioplastics e.V.) is a term used to define two different kinds of plastics: a. Plastics based on → renewable resources (the focus is the origin of the raw material used). These can be biodegradable or not. b. → Biodegradable and → compostable plastics according to EN13432 or similar standards (the focus is the compostability of the final product; biodegradable and compostable plastics can be based on renewable (biobased) and/or non-renewable (fossil) resources). Bioplastics may be - based on renewable resources and biodegradable; - based on renewable resources but not be biodegradable; and - based on fossil resources and biodegradable. Glossary 3.2 last update issue 02/2013 In bioplastics MAGAZINE again and again the same expressions appear that some of our readers might not (yet) be familiar with. This glossary shall help with these terms and shall help avoid repeated explanations such as ‘PLA (Polylactide)‘ in various articles. Since this Glossary will not be printed in each issue you can download a pdf version from our website (bit.ly/OunBB0) bioplastics MAGAZINE is grateful to European Bioplastics for the permission to use parts of their Glossary (see [1]) Readers who would like to suggest better or other explanations to be added to the list, please contact the editor. [*: bM ... refers to more comprehensive article previously published in bioplastics MAGAZINE) Aerobic - anaerobic | aerobic = in the presence of oxygen (e.g. in composting) | anaerobic = without oxygen being present (e.g. in biogasification, anaerobic digestion) [bM 06/09] Anaerobic digestion | conversion of organic waste into bio-gas. Other than in → composting in anaerobic degradation there is no oxygen present. In bio-gas plants for example, this type of degradation leads to the production of methane that can be captured in a controlled way and used for energy generation. [14] [bM 06/09] Amorphous | non-crystalline, glassy with unordered lattice Amylopectin | Polymeric branched starch molecule with very high molecular weight (biopolymer, monomer is → Glucose) [bM 05/09] Amylose | Polymeric non-branched starch molecule with high molecular weight (biopolymer, monomer is → Glucose) [bM 05/09] Biobased plastic/polymer | A plastic/polymer in which constitutional units are totally or in part from → biomass [3]. If this claim is used, a percentage should always be given to which extent the product/material is → biobased [1] [bM 01/07, bM 03/10] Biobased | The term biobased describes the part of a material or product that is stemming from → biomass. When making a biobasedclaim, the unit (→ biobased carbon content, → biobased mass content), a percentage and the measuring method should be clearly stated [1] Biobased carbon | carbon contained in or stemming from → biomass. A material or product made of fossil and → renewable resources contains fossil and → biobased carbon. The 14 C method [4, 5] measures the amount of biobased carbon in the material or product as fraction weight (mass) or percent weight (mass) of the total organic carbon content [1] [6] Biobased mass content | describes the amount of biobased mass contained in a material or product. This method is complementary to the 14 C method, and furthermore, takes other chemical elements besides the biobased carbon into account, such as oxygen, nitrogen and hydrogen. A measuring method is currently being developed and tested by the Association Chimie du Végétal (ACDV) [1] Biodegradable Plastics | Biodegradable Plastics are plastics that are completely assimilated by the → microorganisms present a defined environment as food for their energy. The carbon of the plastic must completely be converted into CO 2 during the microbial process. The process of biodegradation depends on the environmental conditions, which influence it (e.g. location, temperature, humidity) and on the material or application itself. Consequently, the process and its outcome can vary considerably. Biodegradability is linked to the structure of the polymer chain; it does not depend on the origin of the raw materials. There is currently no single, overarching standard to back up claims about biodegradability. One standard for example is ISO or in Europe: EN 14995 Plastics- Evaluation of compostability - Test scheme and specifications [bM 02/06, bM 01/07] Biomass | Material of biological origin excluding material embedded in geological formations and material transformed to fossilised material. This includes organic material, e.g. trees, crops, grasses, tree litter, algae and waste of biological origin, e.g. manure [1, 2] Biorefinery | the co-production of a spectrum of bio-based products (food, feed, materials, chemicals including monomers or building blocks for bioplastics) and energy (fuels, power, heat) from biomass.[bM 02/13] Blend | Mixture of plastics, polymer alloy of at least two microscopically dispersed and molecularly distributed base polymers Bisphenol-A (BPA) | Monomer used to produce different polymers. BPA is said to cause health problems, due to the fact that is behaves like a hormone. Therefore it is banned for use in children’s products in many countries. BPI | Biodegradable Products Institute, a notfor-profit association. Through their innovative compostable label program, BPI educates manufacturers, legislators and consumers about the importance of scientifically based standards for compostable materials which biodegrade in large composting facilities. Carbon footprint | (CFPs resp. PCFs – Product Carbon Footprint): Sum of → greenhouse gas emissions and removals in a product system, expressed as CO 2 equivalent, and based on a → life cycle assessment. The CO 2 equivalent of a specific amount of a greenhouse gas is calculated as the mass of a given greenhouse gas multiplied by its → global warmingpotential [1, 2] Carbon neutral, CO 2 neutral | Carbon neutral describes a product or process that has a negligible impact on total atmospheric CO 2 levels. For example, carbon neutrality means that any CO 2 released when a plant decomposes or is burnt is offset by an equal amount of CO 2 absorbed by the plant through photosynthesis when it is growing. Carbon neutrality can also be achieved through buying sufficient carbon credits to make up the difference. The latter option is not allowed when communicating → LCAs or carbon footprints regarding a material or product [1, 2]. Carbon-neutral claims are tricky as products will not in most cases reach carbon neutrality if their complete life cycle is taken into consideration (including the end-of life). If an assessment of a material, however, is conducted (cradle to gate), carbon neutrality might be a valid claim in a B2B context. In this case, the unit assessed in the complete life cycle has to be clarified [1] Catalyst | substance that enables and accelerates a chemical reaction Cellophane | Clear film on the basis of → cellulose [bM 01/10] Cellulose | Cellulose is the principal component of cell walls in all higher forms of plant life, at varying percentages. It is therefore the most common organic compound and also the most common polysaccharide (multisugar) [11]. C. is a polymeric molecule with very high molecular weight (monomer is → Glucose), industrial production from wood or cotton, to manufacture paper, plastics and fibres [bM 01/10] Cellulose ester| Cellulose esters occur by the esterification of cellulose with organic acids. The most important cellulose esters from a technical point of view are cellulose acetate bioplastics MAGAZINE [04/14] Vol. 9 39
